[aprssig] APRS in-dash display
mcheavens at usa.net
Sun Jan 17 16:37:26 CST 2016
You have not said what make model of car, so I have no idea if I have
any experience with it.
- Other comment from someone else about A and B models only have
composite video, that is not true. The later models (B+ have it, but did
not poplulate the connector).
On 1/17/2016 1:49 PM, Greg D via aprssig wrote:
> Hi Lee, all,
> Yes, sorry. Typo... The Pi has a built-in baseband 640x480 video
> (aka RCA) output, so I won't need the adapter box.
> I'm expecting to run the video through a simple SPDT switch to select
> either the Pi or backup camera. If I get fancy, maybe tie that to the
> car's backup signal and use a relay to switch automatically. No need
> or intention to sacrifice one for the other.
> My expectation is that the system will be on RF primarily, though I
> haven't located a good place for the antenna. I was initially
> thinking to use a small bi-directional tracker-like module (Rx and TX
> required), but will probably start with my Kenwood D7. If I can do
> tethering with my cell phone, I might be on IS too.
> The Accessory outlet does remain on for several minutes after parking,
> but I really need to have something that's automatic because I'd
> likely forget. So, either I make the Pi's file system read-only (so
> it doesn't care about abrubt loss of power), or trigger the shutdown
> automatically. My thought is to put a small 5v NiCd battery on the 5v
> input rail, to hold the Pi running for a bit, and trigger a shutdown
> when the +12 input goes away. I'm not very familiar with the Pi yet,
> so perhaps it has a low power suspend mode, where a small battery
> could hold it for a couple of weeks. That would probably be ideal,
> though I'd still need to trigger the state changes. Haven't had a
> chance to investigate this, beyond recognizing that the issue exists,
> at least in theory. Am I over-designing this?
> On the topic of the operator control, perhaps instead of switches and
> GPIO pins, I recalled after my posting that some cars have essentially
> a joystick mouse-like control mounted between the seats. I'm not sure
> how well this would work on the small screen, but that might solve the
> problem. Anybody have one of these cars, and could relate how it works?
> Greg KO6TH
> Lee Bengston via aprssig wrote:
>> On Jan 17, 2016 12:24 AM, "Greg D via aprssig" <aprssig at tapr.org
>> <mailto:aprssig at tapr.org>> wrote:
>> > Hi folks,
>> > Picking up on a thread I started a while back... Not sure if this
>> will lead to something permanent or not, but I tought I'd give it a try.
>> > I got access to the back of my car's in-dash unit, and the video
>> input connector. It's meant for use with a back camera, which I
>> currently don't have (though it's on the wish list...). Found a VGA
>> to RCA adapter box, and fired up APRSIS32 which was loaded on a small
>> laptop. Here's the result:
>> > http://home.wavecable.com/~ko6th/aprs_dash_display.jpg
>> > http://home.wavecable.com/~ko6th/aprs_laptop.jpg
>> > Given the difficulty, if not questionable legality, of controlling
>> a GUI-based laptop while driving, I think the next steps need to include:
>> > 1. Replace the laptop and VGA adapter with a Raspberry Pi. VGA
>> output is built-in, also much better power draw and small size. (The
>> car is a sports car, so no room for anything bigger.)
>> I think you meant RCA is built in, right?
>> > 2. Replace APRSIS32 with YAAC (for Raspberry Pi compatiblity).
>> > 3. Probably still need a keyboard for full control while parked,
>> but add some fixed key switches tied to keyboard shortcuts for the
>> common stuff while driving. During the earlier exchange, Andrew
>> figured it was a "simple" matter of a Java library to bridge the
>> swtiches to keyboard shortcuts... Hope he's right.
>> > 4. The Pi will boot itself when the car turns on, but I need a way
>> to automatically safely power down the Pi when I turn the car off.
>> Any ideas on this?
>> A lot of vehicles don't shut the radio off immediately - will
>> eventually time out - and many will shut off once you open the door.
>> You could source the power from a source that doesn't shut off right
>> away and buy yourself time to shut down gracefully.
>> Sounds like fun - my truck has a backup camera that I would not want
>> to be without. :-)
>> Lee - K5DAT
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